1. Field of the Invention
The present invention relates to a test management method for an indentation tester, and an indentation tester.
2. Description of Related Art
There has been conventionally known, as a material tester, for example, an indentation tester to form an indentation on a sample surface by pressing an indenter shaft thereonto to measure a physicality value such as a hardness of material. Specifically, for example, the indentation tester measures an indentation depth (an amount of displacement of the indenter shaft) at the time of when a tip of the indenter is pressed onto the sample surface, by a displacement gauge, and obtains a relation between the measured the indentation depth and a test force (burden load) at the time of when the indenter shaft is pressed onto the sample surface to measure a physicality value such as a hardness of sample.
By the way, plastic, thin film material and the like presently become necessary component materials for various machines and structural objects. In recently years, since these materials are often used in a high temperature environment, a request for monitoring a material characteristic at high temperature to help a material development or evaluation has increased.
On the other hand, an instrumented indentation test is most suitable for evaluating plastic or thin film material, which instrumented indentation test is a kind of an indentation hardness test such as Vickers, and measures the test force and the indentation depth point by point in an indentation process so as to obtain various mechanical characteristics of material by analyzing an obtained curve of the test force vs. the indentation depth. An investigation of standardization of a testing method has been promoted, so that a recognizability of the instrumented indentation test has been increased. In particular, the instrumented indentation test according to which the indentation is small is called a nano-indentation or an ultra-micro hardness test, and attracts an attention as a thin film evaluation method.
In order to respond to above request, for example, a sample stage heater (a sample heating device) for heating a sample stage is attached to an instrumented indentation tester, and the sample stage heater heats the sample stage to heat the sample placed on the sample stage.
In the indentation tester, which is not limited to the instrumented indentation tester, to which the sample stage heater is attached, since an indenter shaft contacts with the heated sample or the heated sample stage heats an air around the sample stage, during testing the sample and the like, the indenter shaft is also heated to be thermally-expanded. Moreover, constructional components (a tester frame and the like) of the indentation tester are also thermally-expanded by an influence of high temperature atmosphere. There is a problem that an accurate value (a measurement value) of the indentation depth cannot be obtained when the indenter shaft or the constructional components of the indentation tester are thermally-expanded.
Therefore, for example, there is proposed an indentation tester including: an indenter shaft; a doubly supported beam to the central portion of which the indenter is attached; and a doubly supported beam supporting portion to support the doubly supported beam, wherein at least one of the doubly supported beam and the doubly supported beam supporting portion which are constructional components of the indentation tester is composed of material (specifically, Super Invar) having a small thermal expansion coefficient, and the like (for example, see Japanese Patent Application Laid-Open Publications No. 2004-012178).
Moreover, for example, there is also proposed a method including connecting a stretchable container with a container in an introduction portion, which stretchable container contains: a holding portion (the sample stage) to hold a sample; a heating portion (the sample stage heater) to heat the sample; and an indenter portion, under an inactive gas atmosphere, and which container contains: a loading mechanism to give the burden load to a sample; a load measuring member to measure the load; and a displacement gauge to measure an amount of the indentation of the sample by the load, to reduce a heat influence of a heat conduction or a heat convection from a heat source of the sample stage heater for heating the sample to the loading mechanism or the displacement gauge so as to reduce a heat influence to the value of the indentation depth (the measurement value) (for example, see Japanese Patent Application Laid-Open Publications No. 2002-181679).
However, even in the case of forming the indenter shaft by material having small thermal expansion coefficient or forming the constructional components of the indentation tester by material having small thermal expansion coefficient, the indenter and the constructional components expand with heat to no small extent. Moreover, since an extent of the heat expansion is not known, it is impossible to judge whether or not the measurement value is reliable.
Moreover, even in a case like Japanese Patent Application Laid-Open Publications No. 2002-181679 that the sample stage, the sample stage heater and the indenter are contained in different container from that in which the loading mechanism, the load measuring member, and the displacement gauge are contained, it is impossible to suppress the heat expansion of the sample stage or the indenter (indenter shaft). Furthermore, since an extent of heat expansion is not known, it is impossible to judge whether or not the measurement value is reliable.